The Institute of Electrical and Electronics Engineers (IEEE) has developed two standards for PONs that carry traffic as Ethernet frames. The first is the IEEE 802.3ah Ethernet PON (EPON) standard, commonly referred to as 1G-EPON. The second is the IEEE 802.3av standard, commonly referred to as 10G-EPON. In 1G-EPON, the data rate is one gigabit per second (Gb/s) in both the downstream and upstream direction. In 10G-EPON, the data rate is ten Gb/s in the downstream direction and either one or ten Gb/s in the upstream direction.
The 10G-EPON standard was specified to allow for the simultaneous operation of a 10G-EPON system with a 1G-EPON system over the same set of optical fibers. However, in the upstream direction, the wavebands used by these two systems overlap. Thus, to support coexistence of these two systems over the same set of optical fibers, their respective upstream transmissions are conventionally separated using a pure time-division multiple access (TDMA) scheme; wavelength-division multiple access (WDMA) is not used.
The embodiments of the present disclosure will be described with reference to the accompanying drawings. The drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.